During die casting process,unproper operating will cause crack,corrosion,sticking problem for die casting tooling.The problem will reduce life span of tooling.
There will be several methods to extend life span of tooling
- Heat treatment for tooling material
The die casting tooling working at high pressure,high temperature working condition.Normally,the temperature is from 300℃ to 1000℃ and the pressure if from 150MPa to 500MPa and injection speed if 70m/s – 150m/s,The die casting material normally is lead,zinc,aluminum,cooper etc.
The material for tooling as per following chart
|Die casting Material||Condition||Requirement||Hardness
|Steel for tooling|
|Small mold||Large mold|
|Lead,Zinc,Tin||High pressure,High corrosion,High temperature||Strength,Corrosion resistance,Heat resistance||50-55||45,40Cr||45,40Cr,35CrMo,5CrMnMo|
The properties required by die casting tooling material
- Enough heat resistance and hardness
To avoid deformation and crack caused by high pressure and temperature during injection.
- Good abrasive resistance,oxidation resistance and tempering stability.
To avoid sticking and oxidation when melted alloy is injected into tooling.
- Heat fatigue resistance
The tooling are warming and cooling over and over again,therefore,there will be expand and shrinkage all the time during working.The deformation will happen when thermal stress reach peak.In addition,there will be tiny crack when tooling cavity suffer from corrosion and oxidation.
- High liquation resistance
At 150MPa-500MPa pressure,the casting will cause liquation at high temperature.Therefore,it is necessary for tooling material to resist liquation at high pressure and temperature.
5.Good on through quenching and minimum deformation.
The tooling take method that cavity made by machining before taking to heat treatment.It features high hardness and strength.It is not easy to get thermal fatigue.
6.Good machining ability
Most of cavity are made via machining.Therefore,tooling material required to have good machining ability.The roughness caused by machining should be very small.
7.None of defect for inner texture of tooling material
The defect of inner texture of tooling material will cause crack,thermal fatigue and deformation of tooling.
During usage of die casting tooling,following factors need to be considered.
- Proper injection speed
The tooling will suffer from corrosion and residues will accumulated in core and cavity at high injection speed.Not enough filling and uneven formation will happen at low injection speed.
- The tooling should use one piece of raw material instead of separate raw material made together.
- Strict control of die casting procedure.
- Clean up core and cavity regularly.
- Proper cooling method.
- Regular maintenance of tooling in order to avoid potential damage.